tracing/kprobes: Add argument name support

Add argument name assignment support and remove "alias" lines from format.
This allows user to assign unique name to each argument. For example,

$ echo p do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > kprobe_events

This assigns dfd, filename, flags, and mode to 1st - 4th arguments
respectively. Trace buffer shows those names too.

	<...>-1439  [000] 1200885.933147: do_sys_open+0x0/0xdf: dfd=ffffff9c filename=bfa898ac flags=8000 mode=0

This helps users to know what each value means.

Users can filter each events by these names too. Note that you can not
filter by argN anymore.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090910235337.22412.77383.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Masami Hiramatsu 2009-09-10 19:53:38 -04:00 committed by Frederic Weisbecker
parent e08d1c657f
commit eca0d916f6
2 changed files with 84 additions and 90 deletions

View File

@ -42,7 +42,8 @@ Synopsis of kprobe_events
aN : Fetch function argument. (N >= 0)(*)
rv : Fetch return value.(**)
ra : Fetch return address.(**)
+|-offs(FETCHARG) : fetch memory at FETCHARG +|- offs address.(***)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
(*) aN may not correct on asmlinkaged functions and at the middle of
function body.
@ -62,12 +63,10 @@ enabled:
You can enable/disable the probe by writing 1 or 0 on it.
format:
This shows the format of this probe event. It also shows aliases of arguments
which you specified to kprobe_events.
This shows the format of this probe event.
filter:
You can write filtering rules of this event. And you can use both of aliase
names and field names for describing filters.
You can write filtering rules of this event.
id:
This shows the id of this probe event.
@ -85,10 +84,11 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events
as below.
echo p:myprobe do_sys_open a0 a1 a2 a3 > /sys/kernel/debug/tracing/kprobe_events
echo p:myprobe do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > /sys/kernel/debug/tracing/kprobe_events
This sets a kprobe on the top of do_sys_open() function with recording
1st to 4th arguments as "myprobe" event.
1st to 4th arguments as "myprobe" event. As this example shows, users can
choose more familiar names for each arguments.
echo r:myretprobe do_sys_open rv ra >> /sys/kernel/debug/tracing/kprobe_events
@ -99,7 +99,7 @@ recording return value and return address as "myretprobe" event.
cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format
name: myprobe
ID: 23
ID: 75
format:
field:unsigned short common_type; offset:0; size:2;
field:unsigned char common_flags; offset:2; size:1;
@ -109,21 +109,15 @@ format:
field: unsigned long ip; offset:16;tsize:8;
field: int nargs; offset:24;tsize:4;
field: unsigned long arg0; offset:32;tsize:8;
field: unsigned long arg1; offset:40;tsize:8;
field: unsigned long arg2; offset:48;tsize:8;
field: unsigned long arg3; offset:56;tsize:8;
field: unsigned long dfd; offset:32;tsize:8;
field: unsigned long filename; offset:40;tsize:8;
field: unsigned long flags; offset:48;tsize:8;
field: unsigned long mode; offset:56;tsize:8;
alias: a0; original: arg0;
alias: a1; original: arg1;
alias: a2; original: arg2;
alias: a3; original: arg3;
print fmt: "%lx: 0x%lx 0x%lx 0x%lx 0x%lx", ip, arg0, arg1, arg2, arg3
print fmt: "%lx: dfd=%lx filename=%lx flags=%lx mode=%lx", ip, REC->dfd, REC->filename, REC->flags, REC->mode
You can see that the event has 4 arguments and alias expressions
corresponding to it.
You can see that the event has 4 arguments as in the expressions you specified.
echo > /sys/kernel/debug/tracing/kprobe_events
@ -135,12 +129,12 @@ corresponding to it.
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
<...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: 0x3 0x7fffd1ec4440 0x8000 0x0
<...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: 0xfffffffffffffffe 0xffffffff81367a3a
<...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: 0xffffff9c 0x40413c 0x8000 0x1b6
<...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a
<...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: 0xffffff9c 0x4041c6 0x98800 0x10
<...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a
<...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
<...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: rv=fffffffffffffffe ra=ffffffff81367a3a
<...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=40413c flags=8000 mode=1b6
<...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a
<...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=4041c6 flags=98800 mode=10
<...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a
Each line shows when the kernel hits a probe, and <- SYMBOL means kernel

View File

@ -176,9 +176,14 @@ static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data)
}
/**
* kprobe_trace_core
* Kprobe tracer core functions
*/
struct probe_arg {
struct fetch_func fetch;
const char *name;
};
struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
@ -187,12 +192,12 @@ struct trace_probe {
struct ftrace_event_call call;
struct trace_event event;
unsigned int nr_args;
struct fetch_func args[];
struct probe_arg args[];
};
#define SIZEOF_TRACE_PROBE(n) \
(offsetof(struct trace_probe, args) + \
(sizeof(struct fetch_func) * (n)))
(sizeof(struct probe_arg) * (n)))
static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_trace_func(struct kretprobe_instance *ri,
@ -301,15 +306,21 @@ error:
return ERR_PTR(-ENOMEM);
}
static void free_probe_arg(struct probe_arg *arg)
{
if (arg->fetch.func == fetch_symbol)
free_symbol_cache(arg->fetch.data);
else if (arg->fetch.func == fetch_indirect)
free_indirect_fetch_data(arg->fetch.data);
kfree(arg->name);
}
static void free_trace_probe(struct trace_probe *tp)
{
int i;
for (i = 0; i < tp->nr_args; i++)
if (tp->args[i].func == fetch_symbol)
free_symbol_cache(tp->args[i].data);
else if (tp->args[i].func == fetch_indirect)
free_indirect_fetch_data(tp->args[i].data);
free_probe_arg(&tp->args[i]);
kfree(tp->call.name);
kfree(tp->symbol);
@ -532,11 +543,13 @@ static int create_trace_probe(int argc, char **argv)
* %REG : fetch register REG
* Indirect memory fetch:
* +|-offs(ARG) : fetch memory at ARG +|- offs address.
* Alias name of args:
* NAME=FETCHARG : set NAME as alias of FETCHARG.
*/
struct trace_probe *tp;
int i, ret = 0;
int is_return = 0;
char *symbol = NULL, *event = NULL;
char *symbol = NULL, *event = NULL, *arg = NULL;
unsigned long offset = 0;
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
@ -596,12 +609,21 @@ static int create_trace_probe(int argc, char **argv)
/* parse arguments */
ret = 0;
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
if (strlen(argv[i]) > MAX_ARGSTR_LEN) {
pr_info("Argument%d(%s) is too long.\n", i, argv[i]);
/* Parse argument name */
arg = strchr(argv[i], '=');
if (arg)
*arg++ = '\0';
else
arg = argv[i];
tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
/* Parse fetch argument */
if (strlen(arg) > MAX_ARGSTR_LEN) {
pr_info("Argument%d(%s) is too long.\n", i, arg);
ret = -ENOSPC;
goto error;
}
ret = parse_probe_arg(argv[i], &tp->args[i], is_return);
ret = parse_probe_arg(arg, &tp->args[i].fetch, is_return);
if (ret)
goto error;
}
@ -664,12 +686,12 @@ static int probes_seq_show(struct seq_file *m, void *v)
seq_printf(m, " 0x%p", tp->rp.kp.addr);
for (i = 0; i < tp->nr_args; i++) {
ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i].fetch);
if (ret < 0) {
pr_warning("Argument%d decoding error(%d).\n", i, ret);
return ret;
}
seq_printf(m, " %s", buf);
seq_printf(m, " %s=%s", tp->args[i].name, buf);
}
seq_printf(m, "\n");
return 0;
@ -824,7 +846,7 @@ static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
entry->nargs = tp->nr_args;
entry->ip = (unsigned long)kp->addr;
for (i = 0; i < tp->nr_args; i++)
entry->args[i] = call_fetch(&tp->args[i], regs);
entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
if (!filter_current_check_discard(buffer, call, entry, event))
trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
@ -858,7 +880,7 @@ static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
entry->func = (unsigned long)tp->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
for (i = 0; i < tp->nr_args; i++)
entry->args[i] = call_fetch(&tp->args[i], regs);
entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
if (!filter_current_check_discard(buffer, call, entry, event))
trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
@ -872,9 +894,13 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
{
struct kprobe_trace_entry *field;
struct trace_seq *s = &iter->seq;
struct trace_event *event;
struct trace_probe *tp;
int i;
field = (struct kprobe_trace_entry *)iter->ent;
event = ftrace_find_event(field->ent.type);
tp = container_of(event, struct trace_probe, event);
if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;
@ -883,7 +909,8 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
goto partial;
for (i = 0; i < field->nargs; i++)
if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
if (!trace_seq_printf(s, " %s=%lx",
tp->args[i].name, field->args[i]))
goto partial;
if (!trace_seq_puts(s, "\n"))
@ -899,9 +926,13 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
{
struct kretprobe_trace_entry *field;
struct trace_seq *s = &iter->seq;
struct trace_event *event;
struct trace_probe *tp;
int i;
field = (struct kretprobe_trace_entry *)iter->ent;
event = ftrace_find_event(field->ent.type);
tp = container_of(event, struct trace_probe, event);
if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;
@ -916,7 +947,8 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
goto partial;
for (i = 0; i < field->nargs; i++)
if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
if (!trace_seq_printf(s, " %s=%lx",
tp->args[i].name, field->args[i]))
goto partial;
if (!trace_seq_puts(s, "\n"))
@ -972,7 +1004,6 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
struct kprobe_trace_entry field;
char buf[MAX_ARGSTR_LEN + 1];
struct trace_probe *tp = (struct trace_probe *)event_call->data;
ret = trace_define_common_fields(event_call);
@ -981,16 +1012,9 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
DEFINE_FIELD(unsigned long, ip, "ip", 0);
DEFINE_FIELD(int, nargs, "nargs", 1);
for (i = 0; i < tp->nr_args; i++) {
/* Set argN as a field */
sprintf(buf, "arg%d", i);
DEFINE_FIELD(unsigned long, args[i], buf, 0);
/* Set argument string as an alias field */
ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
if (ret < 0)
return ret;
DEFINE_FIELD(unsigned long, args[i], buf, 0);
}
/* Set argument names as fields */
for (i = 0; i < tp->nr_args; i++)
DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
return 0;
}
@ -998,7 +1022,6 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
struct kretprobe_trace_entry field;
char buf[MAX_ARGSTR_LEN + 1];
struct trace_probe *tp = (struct trace_probe *)event_call->data;
ret = trace_define_common_fields(event_call);
@ -1008,16 +1031,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
DEFINE_FIELD(unsigned long, func, "func", 0);
DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
DEFINE_FIELD(int, nargs, "nargs", 1);
for (i = 0; i < tp->nr_args; i++) {
/* Set argN as a field */
sprintf(buf, "arg%d", i);
DEFINE_FIELD(unsigned long, args[i], buf, 0);
/* Set argument string as an alias field */
ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
if (ret < 0)
return ret;
DEFINE_FIELD(unsigned long, args[i], buf, 0);
}
/* Set argument names as fields */
for (i = 0; i < tp->nr_args; i++)
DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
return 0;
}
@ -1025,31 +1041,21 @@ static int __probe_event_show_format(struct trace_seq *s,
struct trace_probe *tp, const char *fmt,
const char *arg)
{
int i, ret;
char buf[MAX_ARGSTR_LEN + 1];
int i;
/* Show aliases */
for (i = 0; i < tp->nr_args; i++) {
ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
if (ret < 0)
return ret;
if (!trace_seq_printf(s, "\talias: %s;\toriginal: arg%d;\n",
buf, i))
return 0;
}
/* Show format */
if (!trace_seq_printf(s, "\nprint fmt: \"%s", fmt))
return 0;
for (i = 0; i < tp->nr_args; i++)
if (!trace_seq_puts(s, " 0x%lx"))
if (!trace_seq_printf(s, " %s=%%lx", tp->args[i].name))
return 0;
if (!trace_seq_printf(s, "\", %s", arg))
return 0;
for (i = 0; i < tp->nr_args; i++)
if (!trace_seq_printf(s, ", arg%d", i))
if (!trace_seq_printf(s, ", REC->%s", tp->args[i].name))
return 0;
return trace_seq_puts(s, "\n");
@ -1071,17 +1077,14 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
{
struct kprobe_trace_entry field __attribute__((unused));
int ret, i;
char buf[8];
struct trace_probe *tp = (struct trace_probe *)call->data;
SHOW_FIELD(unsigned long, ip, "ip");
SHOW_FIELD(int, nargs, "nargs");
/* Show fields */
for (i = 0; i < tp->nr_args; i++) {
sprintf(buf, "arg%d", i);
SHOW_FIELD(unsigned long, args[i], buf);
}
for (i = 0; i < tp->nr_args; i++)
SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");
return __probe_event_show_format(s, tp, "%lx:", "ip");
@ -1092,7 +1095,6 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
{
struct kretprobe_trace_entry field __attribute__((unused));
int ret, i;
char buf[8];
struct trace_probe *tp = (struct trace_probe *)call->data;
SHOW_FIELD(unsigned long, func, "func");
@ -1100,10 +1102,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
SHOW_FIELD(int, nargs, "nargs");
/* Show fields */
for (i = 0; i < tp->nr_args; i++) {
sprintf(buf, "arg%d", i);
SHOW_FIELD(unsigned long, args[i], buf);
}
for (i = 0; i < tp->nr_args; i++)
SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");
return __probe_event_show_format(s, tp, "%lx <- %lx:",
@ -1140,7 +1140,7 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
entry->nargs = tp->nr_args;
entry->ip = (unsigned long)kp->addr;
for (i = 0; i < tp->nr_args; i++)
entry->args[i] = call_fetch(&tp->args[i], regs);
entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
perf_tpcounter_event(call->id, entry->ip, 1, entry, size);
} while (0);
return 0;
@ -1175,7 +1175,7 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
entry->func = (unsigned long)tp->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
for (i = 0; i < tp->nr_args; i++)
entry->args[i] = call_fetch(&tp->args[i], regs);
entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
perf_tpcounter_event(call->id, entry->ret_ip, 1, entry, size);
} while (0);
return 0;